1. Field of the Invention
This invention relates to a bar-code information reading apparatus for reading bar-code information, and more particularly to a bar-code information reading apparatus for storing bar codes into a memory by use of small memory capacity.
2. Description of the Related Art
Conventionally, various types of bar codes are widely used to manage articles, packages and the like.
In a bar-code information reading apparatus for reading and decoding such a bar code, a method of scanning the bar code by use of a laser or picking up an image of the bar code by use of a linear sensor or area sensor is conventionally used as the bar-code reading method. More specifically, in the case of a laser system, a laser beam spot is scanned on the bar code and the intensity of light reflected from the scanned area is sequentially detected. In the case of a linear sensor or area sensor, a bar code image is formed on the sensor by use of an optical system and information of light amount detected by elements of the sensor is serially read.
It is determined by the standard of ordinary bar codes that a blank portion called a quiet zone is provided around the bar code. Therefore, the blank portion in which no bar code is present is first read in the scanning operation when white-and-black information of the bar code is read by the above methods.
However, if the blank portion is large, a large amount of information which is not necessary for decoding the bar code will be read and stored into the memory, the memory capacity is vainly used and time for decoding becomes longer than necessary.
Therefore, various methods of starting the operation of reading and storing bar-code information without reading a large part of the blank portion into the memory are proposed.
For example, in Jpn. Pat. Appln. KOKAI Publication No. 4-268982, a reading apparatus for reading one of bar code information items into a decoding section for decoding when a plurality of bar codes come into the reading area of the line sensor is disclosed. In the reading apparatus disclosed in the above patent specification, only a count value of a bar code having a starting position set in the reading permission range is written into a count value memory and decoded. That is, in the reading apparatus disclosed in the above patent specification, the presence of a bar code is determined when the quiet zone on the starting side is detected and then the operation of reading and storing of the bar-code information is started.
However, in the prior art disclosed in the above patent specification, the quiet zone is used to detect the starting position of the bar code so that the starting position of the bar code cannot be detected and the operation of reading and storing of the bar code cannot be started when the width of the blank portion around the bar code is less than a specified value.
Further, even when the width of the blank portion is equal to or larger than a specified value, only the blank portion of the width smaller than the specified value can be detected when a stain such as void is present, and in this case, the reading and storing operation cannot be started.
In contrast, when the blank portion is excessively large, data of the blank portion prior to starting of the bar code is stored since the reading and storing operation is started after the quiet zone is read in the prior art disclosed in the above patent specification. As a result, a large amount of useless information having no relation to the bar code information is stored into the memory, and thus, the memory capacity of the memory is vainly used and time for decoding becomes longer than necessary.